What is chemical or organophosphate poisoning?

Organophosphate poisoning results from exposure to organophosphates (OPs), which cause the inhibition of acetylcholinesterase (AChE), leading to the accumulation of acetylcholine(ACh) in the body, resulting in the nerves becoming overactive. Organophosphate poisoning most commonly results from exposure to insecticides or nerve agents. OPs are one of the most common causes of poisoning worldwide, and are frequently intentionally used in suicides in agrarian areas. There are around 1 million OP poisonings per year with several hundred thousand resulting in fatalities annually.

 

• What are organophosphates?
• Signs & Symptoms
• General Treatment Options
• What Happens in Intensive Care?
• How long will your loved one remain in Intensive Care?
• Weblinks

 

What are organophosphates?

Organophosphates are chemicals used in domestic and industrial settings, most commonly as insecticides. Examples are

• Insecticides including malathion, parathion, diazinon, fenthion, dichlorvos, chlorpyrifos, ethion
• Nerve Gases including soman, sarin, tabun, VX
• Ophthalmic agents: echothiophate, isoflurophate
• Antihelmintics such as trichlorfon
• Herbicides including tribufos [DEF], merphos are tricresyl phosphate–containing industrial chemicals

Exposure to any one of the above listed organophosphates occurs on a daily basis through inhalation, absorption, and ingestion, most commonly of food that has been treated with an organophosphate herbicide or insecticide. Exposure to these chemicals can occur at public buildings, schools, residential areas, and in agricultural areas. The chemicals chlorpyrifos and malathion have been linked to reproductive effects, neurotoxicity, kidney/liver damage, and birth defects. Dichlorvos has also been linked to reproductive effects, neurotoxicity, and kidney/liver damage, as well as being a possible carcinogen. The severity and onset of symptoms is dependent on the degree of exposure.

Signs & Symptoms

The health effects associated with organophosphate poisoning are a result of excess acetylcholine (ACh) present at different nerves and receptors in the body because acetyocholinesterase is blocked. Accumulation of ACh at motor nerves causes overstimulation of nicotinic expression at the neuromuscular junction. When this occurs symptoms such as

• muscle weakness
• fatigue
• muscle cramps
• fasciculation
•  paralysis
• tachycardia
• hypertension
• hypoglycemia
• anxiety
• headache
• convulsions
• ataxia
• depression of respiration and circulation
• tremor
• general weakness
• potential coma
• visual disturbances
• tightness in chest
• wheezing due to bronchoconstriction
• increased bronchial secretions
• increased salivation
• lacrimation
• sweating
• peristalsis
• urination

can be seen.

General Treatment Options

The Patient with organophosphate poisoning requires decontamination, and those in contact with the Patient must use personal protective equipment (PPE) to avoid absorption of the chemical. This decontamination consists of thoroughly washing the Patient, including hair. Clothing must be washed and any leather article discarded (chemical cannot be removed from leather).

Specific treatment will depend upon how the Patient became poisoned and their level of symptoms. If the Patient has swallowed the poison recently they will receive activated charcoal by mouth to absorb the residual poison.

The medication Atropine is a muscarinic antagonist, and thus blocks the action of acetylcholine peripherally. These antidotes are effective at preventing lethality from OP poisoning, but current treatment lack the ability to prevent post-exposure incapacitation, performance deficits, or permanent brain damage.

What Happens in Intensive Care?

Once your loved one has been admitted to ICU their care will be focused on monitoring their level of cholinesterase and the residual effects of the poisoning on the Patient. Treatment will be supportive. Once in Intensive Care your loved one will be cared for in a single room with special ventilation and any staff caring for your loved one will continue to wear protective clothing for a number of days.

• Initially oxygen and respiratory support might be commenced via an oxygen mask or via Non- Invasive Ventilation(NIV) or BIPAP ventilation
• Full ventilation using a Ventilators(Breathing Machine) and a Breathing Tube (endotracheal tube) may be required to improve and maintain the oxygen delivery
• Sedation may be used if your loved one is in an induced coma
• Your loved one will require monitoring using a Bedside Monitors and an Arterial Catheter(Arterial Line)
• You can expect your loved one to have frequent Chest X-rays and blood tests(Blood& Pathology tests in Intensive Care) especially arterial blood gases (ABGs)
• Infusion pumps are administering drugs to support your loved ones blood pressure and haemodynamic system, as well as intravenous fluids may be administered via a central venous catheter/ CVC(Central Venous Lines)
• An NG Tube (Nasogastric Tubes) is usually inserted into your loved ones stomach, in order to commence nutrition or to remove fluids
• Urine Output is usually measured hourly, after insertion of a Urinary Catheter

How long will your loved one remain in Intensive Care?

Your loved one will stay in ICU until the signs of respiratory failure have subsided. The degree of exposure to the chemicals, and the symptoms experienced, will determine how long the Patient stays in hospital.

Weblinks

• Health Surveillance Guideline
• Poisons Information Centres Across Australia – 131126
• Bayer Product Information
• http://www.aapcc.org/  Poison information service USA
• http://www.npis.org Poison information service UK

Any Questions?

Of course, if you have any questions or concerns, please discuss them with the ICU nurses and doctors.

All Intensive Care interventions and procedures carry a degree of potential risk even when performed by skilled and experienced staff. Please discuss these issues with the medical and nursing staff who are caring for your loved one.

The information contained in this sheet is general in nature and therefore cannot reflect individual Patient variation. It is meant as a back up to specific information which will be discussed with you by the Doctors and Nurses caring for your loved one. INTENSIVE CARE HOTLINE attests to the accuracy of the information contained here BUT takes no responsibility for how it may apply to an individual Patient. Please refer to the disclaimer.

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